Corrosion damage in industrialized countries is a major problem with the resultant costs for replacement of damaged parts, with the dangers from affected structures such as bridges, pipes, storage tanks and other large metal structures, and with the degraded appearance of, e.g., cars and buildings subjected to corrosion. Increasingly, corrosion prevention techniques have been sought to reduce the total costs of such corrosion. Painting is the most common method of preventing corrosion of mild steel which is the most widely used construction material. Various techniques have been employed in paint systems in the efforts to control corrosion. Among these are the use of anti-corrosive pigments such as zinc chromate or in many large fixed structures the use of cathodic protection such as by galvanic protection or by impressed current. Cathodic electrodeposition has been widely used for corrosion protection in, e.g., the automotive industry, but the process is not as well adapted to large fixed steel structures.
Electroactive coatings such as polyaniline coatings upon steel substrates have been described, by DeBerry in J. Electrochemical Society, Vol. 132, No. 5, pp. 1022-1026 (1985), as providing a type of anodic protection to such substrates within an acidic environment. Other types of electroactive materials such as indium-tin oxide coatings, described by Jain et al. in Corrosion-NACE, Vol. 42, No. 12, pp. 700-707 (1986), or phthalocyanine coatings described, by Hettiarachchi et al. in Proc. Electrochem. Soc., Vol. 89-1, pp. 320-325 (1989) have also been suggested as providing corrosion protection to substrates.
Accordingly, it is an object of this invention to provide a process of reducing corrosion to metallic substrates and particularly reducing corrosion to large metallic substrates such as, e.g., bridges, storage tanks, and space vehicle launch support structures.
It is a further object of this invention to provide a coating composition for reducing corrosion to metallic substrates.
It is a still further object of this invention to provide a coated article having reduced corrosion upon its metallic components.